US 7372479 B2
An image forming apparatus for forming images with an electrophotographic system. The image forming apparatus includes a laser drive unit configured to control a laser light, and an image data transfer control unit configured to control image data from to the laser drive unit. The apparatus also includes a polygon mirror configured to reflect laser light from the electrophotographic system, a polygon mirror drive unit including a motor configured to rotate the polygon mirror, and a power supply level detecting unit configured to detect a voltage level of power supplied to the polygon mirror drive unit by an electric power supply unit. The image data transfer control unit is configured to provide any width and any number of a first pulse signal indicating a state when power supply is cut off to the polygon mirror drive unit.
1. An image forming apparatus for forming images with an electrophotographic system, said image forming apparatus comprising:
a laser drive unit configured to control a laser light;
a polygon mirror configured to reflect the laser light;
a polygon mirror drive unit including a polygon motor and configured to rotate said polygon mirror;
an electric power supply unit configured to supply electric power to the polygon mirror drive unit;
a polygon motor operation condition signal generating device configured to generate an operation condition signal in accordance with an operation condition of the polygon motor;
a first pulse signal generating device configured to generate a first pulse signal having a prescribed level and frequency when the electric power supply unit stops supplying power;
a second pulse signal generating device configured to generate a second pulse signal based on the polygon motor operation condition signal and the first pulse signal; and
an error occurrence determining device configured to determine which one of the polygon mirror drive unit and the electric power supply unit is in an abnormal condition based on the second pulse signal.
2. The image forming apparatus according to
3. The image forming apparatus according to
4. The image forming apparatus according to
5. The image forming apparatus according to
6. The image forming apparatus according to
7. The image forming apparatus according to
8. The image forming apparatus according to
9. The image forming apparatus according to
a developer cartridge configured to accommodate a developer;
an image carrier configured to receive a latent image; and
a developer carrier configured to supply developer to the image carrier,
wherein a removable unit including the developer carrier and the developer cartridge is removable from the image forming apparatus,
wherein a detecting unit is configured to detect a presence of the removable unit when the removable unit is attached to the image forming apparatus, and
wherein the detecting unit is configured to produce a signal indicating the presence of the removable unit, the signal being supplied to the error determining device.
This patent document is based on and claims priority to Japanese patent application No. 2004-194313 filed on Jun. 30, 2004, the entire contents of which are hereby incorporated herein by reference.
1. Field of the Invention
The present invention generally relates to the field of image forming devices such as, for example, copiers and printers. More specifically, the present invention relates to optical control for image formation in image forming devices.
2. Description of the Background Art
In the background art, an image forming apparatus such as a laser printer turns a light on and off according to the image data. The apparatus rotates a polygon mirror by a certain number of rotations according to a resolution (recording density) of the image data. The laser light emitted from a laser diode is scanned with a polarized light by the polygon mirror rotated by a motor, and the apparatus forms images by projecting the laser light on a pre-charged photosensitive drum.
After a predetermined time has passed from when the motor was driven in the image forming apparatus, the number of rotations (RPM: rotations per minute) is checked to determine if an error is present by measuring the current flowing in the motor. And when an error, such as a motor lock, is detected by the current flowing in the motor, an error correction process is executed against the error.
Japanese Laid-Open Patent Publication No. 2003-259677 describes an invention in which an ambient temperature of an exposure unit detected by a temperature sensor is compared with a predetermined temperature. If the ambient temperature is higher than the predetermined temperature, an operation environment of the motor is judged to be better than a predetermined level, and thus the period of time between error judgments (i.e. the judgment permission time) is set to a short value. Further, the apparatus does not make an error judgment until a passing time from the output time of a driving control signal to a motor driving circuit reaches the judgment permission time. The apparatus makes an error judgment based upon the passing time and the ambient temperature.
Japanese Laid-Open Patent Publication No. 2002-64927 describes a system that includes a power supply control unit that controls whether electricity is supplied to an electric component, and an electric component control unit outputs a control signal to the power supply control unit. The system monitors a conduction of a power distribution in the electric component, and the system is reset when the system turns on for a period of time that is longer than a preset time. And the system reset is repeated until the electric component reaches a normal operating condition. If the system does not recover when the reset frequency reaches a preset number, an electric power supply is cut off. The interruption control of the power supply to the system is executed by monitoring of the preset time.
Japanese Laid-Open Patent Publication No. H7-294839 describes a timing changing means that changes the detection timing for checking for an error in a number of rotations of a motor. When the rotation of the motor is signaled to stop, the apparatus decides whether it stops the rotation immediately according to the detected number of rotations or whether it reduces the speed of the rotation and then stops the rotation. In the latter case, the apparatus can also restrict the detection of the error for a certain number of rotations.
Japanese Laid-Open Patent Publication No. H8-156316 describes a control of an applied voltage and plural motors. In a standby mode, an applied voltage is 12V. A driving motor is controlled to a number of N3 rotations. In a copy operation mode, at first the driving motor of the first polygon mirror is applied the standby mode voltage, then the applied voltage is increased to 24V and the number of rotations becomes N5 during the writing operation. When a voltage detection unit detects 18 V, the voltage detection unit outputs a detection signal to the control unit. The control unit outputs a voltage supply signal to the second polygon mirror and activates a second driving motor. In the same way, when the applied voltage of the second driving motor becomes 18 V, then a third driving motor of the third polygon mirror is activated. And when the voltage of the third driving motor becomes 18 V, then a fourth driving motor of the fourth polygon mirror is activated. And a rotation of each polygon mirror is increased sequentially to the number of rotations used in an optical writing. Using this method, it is possible to reduce electric power consumption by providing a time lag for the activation of the driving motors, and an operating time of the first copy is stable using such a control system.
Japanese Laid-Open Patent No. 2003-90976 describes a light polarization unit that drives the rotation of rotating parts with mirrors using a motor. The apparatus includes a temperature sensor for detecting a temperature of the motor, a fan for cooling off the motor, and a fan control unit for controlling the number of rotations of the fan. Using this configuration, it is possible to reduce a rise in temperature and to increase the cooling efficiency of the motor by using an air-cooling system. It is further possible to reduce electricity use using an over-speed rotation of the fan.
Japanese Laid-Open Patent Publication No. 2000-3115 describes a mechanical switch that attaches with an apparatus and is activated by an operating part of a process cartridge. The switch detects the process cartridge. The switch cover is closed only when a process cartridge is detected. The apparatus turns a photosensitive drum with a driving gear of an image support unit. Using this configuration, a connection error of connector between apparatus and a non-volatile memory (NVRAM) is eliminated, and it is possible to detect an error of the NVRAM itself.
However, in the above-mentioned background art, an environmental temperature, a passing time, a number of rotations, a changing state of applied voltage, and an error judgment are determined by monitoring an electric component in a motor control of a polygon mirror. These documents do not describe detecting and monitoring an interception state of a power supply voltage applied to the motor from outside. For example, when a power supply voltage (normally +24V) from a power supply to a motor is cut off by some factor, the motor driving unit cannot operate. As a result, a state signal (e.g., a polygon stack signal) becomes an inactive state, and an error outbreak is notified to the system. Further, since the error state is displayed as the error (polygon motor stack error) from the motor drive means, the error in the power supply is not displayed. Accordingly, it becomes difficult to specify a cause of the error.
Furthermore, in the invention described in JP 2000-3115, a notification means stops the operation of the unit and notifies an operator of this state when a process cartridge is not completely loaded. However, this system allows for the detection of only NVRAM. As a result, a control of the other units when errors occur in those other units is not described in the document.
The present invention advantageously provides an apparatus for optical writing control, and a method for such control that can easily judge an error state of the apparatus when a power supply to the polygon mirror driving unit is interrupted or lost.
An image forming apparatus is provided that forms an image using an electrophotographic system that includes a laser driving unit controlling a laser light. The apparatus also includes an image data transferring control unit transferring and controlling an image data from upper apparatus to the laser drive unit, a polygon mirror reflecting a laser light from the laser light source, a polygon mirror driving unit driving a motor for rotating the polygon mirror, an electric power supply unit supplying an electric power to the polygon mirror driving unit. The image forming apparatus further includes a power supply level detecting unit that detects a voltage level of the applied power supply to the polygon mirror driving unit from the electric power supply unit. Furthermore, the apparatus is configured to send a pulse signal having any width and any numbers which shows a state when the applied power supply is cut off to the power supply level detecting unit.
According to an alternate embodiment, a method for forming images with an electrophotographic system is disclosed, including the steps of controlling a laser light, controlling to transfer image data from an upper-apparatus to a laser driver unit, and reflecting laser light from laser light source. The method further includes the steps of driving a motor for controlling a rotation of the polygon mirror, supplying an electric power to the motor, and detecting the voltage level of the power supplied to the motor. The method gives any width and any number of pulse signal shown a state when a power supply was cut off to the applied power supply level detecting unit.
In the following drawings, like references numerals will be used to refer to like elements in the various drawings, in which:
An embodiment of the present invention is explained referring to the attached drawings.
The description below describes the operation of the various components such as FAX control unit 102, printer control unit 104, input image processing unit 106, key operation unit 107, main control unit 108, and writing control unit 110 incorporated into various embodiments. For example, in the case of a copy operation, the main writing control unit 108 transfers image data from input image processing unit 106 to the writing control unit 110. It further continues producing a plurality of prints by repeating data processing in a main scanning direction and a sub-scanning direction using writing control unit 110 (a color writing unit shown in
The engine unit forms a latent image on a photosensitive belt 203 a by a laser light exposed from writing unit 201. The belt 203 a is charged and discharged using the photosensitive drum cleaning unit 205 and the charging brush 203 with the discharge unit 204.
Once the latent image is formed on the belt 203 a it is transferred to an intermediate transfer belt 206, using the first transfer brush 208. A sheet is fed from a paper feed tray 209 to the second transfer roller 210 and the image is transferred from the belt 206 to the sheet. The formed image is thermally fixing on the sheet in fixing unit 211 and goes through divergence unit 212. It further passes by either eject course to the top of the main body or duplex printing unit 213.
By means of the above-mentioned serial movement, a printing is executed on the basis of the printing data which is input over writing control unit 201. In addition, it repeats the serial movement in each color in the case of color printing in two or more colors.
An embodiment of the present invention is explained with reference to
Laser Diode (LD) driving unit 305 includes writing control unit 110 shown in
The power supply level detection unit 304 has inputs of +24V voltage from power supply unit 301, a polygon mirror state signal from polygon mirror driving unit 303, and a count value from CPU 306.
The details of the internal circuitry of power supply level detection unit 304 are depicted in
On the other hand, in
As each counter outputs (Q1, Q2, etc.) are output according to a value of a pre-set load data, it is made a logical operation (in the case exclusive or: EXOR) with any output signals and original XSCRDY signal. As thus described, a counter output with any width shown in
On the other hand, concerning a number of counter output pulses, it is possible to control an output pulse number an operation of counter is stopped by detecting +24 V cut state inside the power supply unit 301 and providing a count stop signal (which, in this embodiment is an “L” level signal) at any time from CPU 306. By this, it is possible to generate any width and any number of pulse signal(s). The pulse signal is synchronized with a clock signal (PMCLK) supplied by the polygon mirror driving unit. The polygon clock signal (PMCLK) is input through polygon mirror drive unit 303 shown in
In the above construction, the relationship among width, number of pulse signal(s), and number of polygon face(s) in an error state is shown by, for example, as polygon frequency, f, becomes f=M/10 (M: rotation number per minutes), a generated pulse width also becomes a number in proportion to the number of polygon faces. As a result, it becomes easy to control an error state of the motor especially. The apparatus is composed to set any value from CPU 306 against a counter setting value shown in
Further, the pulse width and number are provided by the setting input from an external input unit provided in the image forming apparatus. These values are set against CPU 306 from operation unit 308. Operation unit 308 is equivalent to operation unit 107 shown in
Furthermore, as a pulse signal that is output to the laser drive unit 305 is overlapped with a state signal output from the polygon mirror drive unit, the counter output Qn shown in
In the case of
On the other hand, in
In the case of
On the other hand, in
In the case of
On the other hand, in
In the case of
A mechanism is now explained that does not judge an error of the polygon mirror drive unit when a particular pulse signal that is overlapped with a state signal output from polygon mirror drive unit is detected with a unique sampling frequency.
A digital full color copier having 1 drum is shown in the embodiment disclosed herein; however Tandem type machine that has four drums can be applied for machinery of a mono color without distinction of the kind.
An example of a photoconductor unit (process cartridge) is depicted in
Transfer unit 510 is provided in a diagonal course and is configured to convey paper from the right lower part as shown in
The main body of the photoconductor unit will now be explained with reference to
The developing unit 9 includes a toner density sensor 9E, which detects the toner density and controls toner density. The charging of photosensitive drum (or image carrier) 3 is performed by charging roller 7. Charging roller 7 rotates in a reverse direction to a drum. The charging roller 7 provides a uniform electric charge on the drum 3. In the upper part of the charging roller 7, a charge cleaning roller 7A is installed permanently with charging roller 7. The charge cleaning roller 7A cleans the charging roller 7.
Unused toner on the photosensitive drum 3 is collected using a cleaning blade 11B and a cleaning brush 11A in cleaning unit 11. Cleaning blade 11B is installed in an inclined manner in a counter direction against a drum rotation and is established permanently with a drum. Cleaning brush 11A is rotated in a direction opposite to the rotation of the drum 3. It is mixed with a blade and unused toner is collected. The unused toner is sent to a toner conveyance screw 11C. The unused toner is conveyed by the toner conveyance screw 11C to an unused toner vent and collected by an unused toner bottle (not shown).
Nonvolatile memory is provided in memory tag 12, which stores that information necessary for control of each photosensitive drum unit (a process cartridge unit), cartridge identification (ID), the production date, age or date of first use, recycling frequency, the date as of the copy number of sheets, etc. In addition, a tag of the contact type that carries an integrated circuit (IC) chip, a tag which carries a non-contact type IC chip or a non-contact type chip card may be carried instead of the nonvolatile memory (NVRAM) tag 12.
Next the image formation process is explained. The photosensitive drum 3 is driven to rotate at a predetermined speed. While the photosensitive drum 3 rotates, it receives a uniform charge of electricity of an original or negative predetermined electrical current potential from the charging unit 7. Image exposure light is received from an image exposure unit, such as writing system 500 (
The transfer materials that received transcription are separated from the surface of the photosensitive drum 3, and introduced into an image fixing unit in order to fix the image thereto. The surface of the photosensitive drum 3 after image transcription is cleaned of any remaining toner by cleaning unit 1. Further, the photosensitive drum 3 can be used repeatedly in this manner for image formation after the electricity is removed.
In the above configuration, the image formation unit of the present embodiment includes a mecha switch (a mechanical switch) as a unit attachment detect unit that detects whether a process cartridge is attached. When a process cartridge is loaded in the image forming unit using a mounting means, the mechanical switch turns ON by fitting in a reentrant of the image formation unit and the attachment of the process cartridge is detected through the installation of an operation piece from a toner bottle.
A procedure for detecting a cartridge presence and for detecting a strange medium error when a process cartridge is mounted to the image formation unit in now explained. In order perform an image formation in the image formation unit of the present embodiment, an opening and shutting cover of the image formation unit is first opened, and then a process cartridge is loaded at a prescribed position. At this time, the connectors that are connected to the memory tag 12 of the process cartridge are connected to the image formation unit.
When the connectors of the memory tag 12 are connected, a mechanical switch detects the presence of the process cartridge when the switch is actuated. When the mechanical switch is not actuated, then it is judged that a process cartridge is not present. When the mechanical switch is actuated, thereby detecting the presence of a process cartridge, then a cartridge attachment and detachment state signal is transmitted to the CPU 306 in the image formation unit (
Further, regarding the closing of an opening and shutting cover for the image formation unit, if loading of a process cartridge is detected by the mechanical switch, a portion of the process cartridge is approached by connectors of the image formation unit connected to an NV-RAM by turning of a gear driving an image body to the drive unit and photosensitive drum to the image formation unit.
In this way a process cartridge and state of attachment with the image formation device unit are detected during attachment and detachment, and it can be detected if a process cartridge unexpected falls off or becomes loose/disconnected during a printing operation and controls a unit interlocked thereto (e.g., polygon mirror drive unit) in such a situation.
The above embodiments utilize a polygon mirror drive unit, an LD drive unit, and other image formation unit printing of an electrophotographic system. However, it is possible to apply the above invention to other types of image forming apparatuses.